Multimedia, e.g., audio and/or video, playback and/or collecting (receiving, capturing, recording, etc) are popular and even essential functions of modern electronics, such as mobile phones, smart phones, tablet/notebook computers, wearable gadgets, digital cameras and camcorders, navigators (e.g., satellite positioning electronics), surveillance apparatuses, hand-held devices and portable computers. To handle multimedia playback and collecting, conventional architecture integrates analog-to-digital converter (ADC) and digital-to-analog converter (DAC) into a codec chip to cooperate with a main chip, such as a CPU, an application processor or a baseband processor. The codec chip and the main chip interchange signals via an inter-chip connection mechanism.
For example, to accomplish audio playback and collecting, the codec chip bridges the main chip to one or more speakers and one or more microphones. For audio playback, the main chip provides digital audio signals to be played, which are transmitted to the codec chip via the inter-chip connection mechanism, and are converted to analog output signals by the codec chip to actuate the speakers. For audio collecting, the codec chip converts analog audio signals picked by the microphones to digital signals, which are then transmitted to the main chip via the inter-chip connection mechanism.
In prior arts, the inter-chip connection mechanism relaying digital audio signals between the main chip and the codec chip is implemented by I2S (inter-IC sound) bus or Slimbus. For bi-directional interchange of 2-channel stereo digital audio signals between the main chip and the codec chip, I2S requires at least three inter-chip wires, so the main chip needs three balls (pins) and the codec chip need another three balls. If more channels are demanded, I2S requires more wires and therefore more balls of both the main chip and the codec chip. Consequently, I2S bus suffers high pin-count (count of balls) and complex inter-chip wiring.
On the other hand, Slimbus can support bi-directional digital audio interchange of many channels by two-wire inter-chip communication between the main chip and the codec chip. However, Slimbus needs to implement complex network layers, including physical layer, frame layer and higher layers of message protocol and transport protocol, for both of the main chip and the codec chip. Consequently, Slimbus suffers high hardware complexity and area overhead for both of the main chip and the codec chip.